There is a need within the pharmaceutical industry to produce an opening in the surface of many types of dosage forms. For example, certain controlled release devices rely on an opening which extends from outside the device, through an outer coating or housing and into the core of the device, as a means of releasing material stored within the core to the environment of use.
Often these controlled release devices rely on osmotic pressure, diffusion or surface hydration to deliver the contents of the core through the opening.
U.S. Pat. No. 4,088,864 reported the use of a laser to produce outlet passage-ways in the walls of pills which dispense their contents osmotically. This technique comprised moving the pills in succession along a predetermined path at a predetermined velocity; tracking the moving pills seriatim with a laser of a wavelength which is absorbable by the walls. The laser beam dimensions at the wall, the laser power and the firing duration were such as to cause the laser beam to heat and pierce the wall and produce an outlet passageway 4 to 2000 microns in diameter through the wall and into the device core.
There is further a need to produce dosage forms containing multiple holes through the dosage form and into the core of the dosage form. Application Ser. No. 07/815,304, filed Dec. 28, 1991, for example, relies in part on multiple holes drilled through a water impermeable membrane. The holes expose multiple portions of the dosage form core to the environment of use, allowing for delivery of the drug stored within the core.
Jain, N. K. and Naik S. U., J. Pharm Sci., 73, 1806-1811 (1984), have reported on the use of a laser to drill holes in capsules. To vary the number of pores, the capsule was mounted on a linear drive and moved at a speed of 2 mm/sec. By changing the laser frequency and keeping the power and pulse width constant 25 to 100 pores were drilled on the body of the capsule shell.
Technology required to produce multiple patterns of openings through the dosage form shell or coating without repositioning of the dosage form has previously not been available. A process which provides for rapid throughput of dosage forms, capable of providing such a pattern of openings, without such manipulation is desirable.
Recently, laser systems which employ a linear array of individual laser tubes have been developed. These systems allow the user to pulse only those lasers needed so as to produce a linear array of laser beams. In U.S. Pat. No. 5,049,721, such a system was used to provided markings in an outer jacket of repetitively spaced sections along the length of a moving cable. As the cable was moved along, the lasers were pulsed, via a computer program, to produce the letters and symbols.
Applicants have found a novel use for this technology in the chemical delivery field, in that multiple arrays of holes can be drilled in dosage form devices more rapidly and precisely than heretofore thought possible.